Abstract: Structural changes in amorphous LixSi during the initial lithiation of single
crystal Si to amorphous LixSi were investigated as a function of Li flux and
total charge using solid-state 7Li nuclear magnetic resonance (NMR)
spectroscopy. Single crystal (100) Si wafers were used as a model system in
this study, as the Li flux could be precisely controlled and uniformly
distributed across the surface of the wafer. It was observed that peak shifts
in solid-state 7Li NMR spectra varied as a function of the Li flux during the
initial lithiation and stayed constant for samples of the same Li flux
regardless of the total charge applied to the electrodes. We conclude from
these results that the Li concentration in LixSi stays constant for a given
flux regardless of the total coulombic charge applied to the electrode. The
results from this study help better understand the kinetics, the reaction
mechanisms, and the kinetic modeling of chemical reactions at the reaction
front during the initial lithiation of Si (100).